function hasOwnProperty(obj, prop) {
    return Object.prototype.hasOwnProperty.call(obj, prop);
}

export function decode(qs, sep?: string, eq?: string, options?: any) {
    sep = sep || '&';
    eq = eq || '=';
    var obj = {};

    if (typeof qs !== 'string' || qs.length === 0) {
        return obj;
    }

    var regexp = /\+/g;
    qs = qs.split(sep);

    var maxKeys = 1000;
    if (options && typeof options.maxKeys === 'number') {
        maxKeys = options.maxKeys;
    }

    var len = qs.length;
    // maxKeys <= 0 means that we should not limit keys count
    if (maxKeys > 0 && len > maxKeys) {
        len = maxKeys;
    }

    for (var i = 0; i < len; ++i) {
        var x = qs[i].replace(regexp, '%20'),
            idx = x.indexOf(eq),
            kstr, vstr, k, v;

        if (idx >= 0) {
            kstr = x.substr(0, idx);
            vstr = x.substr(idx + 1);
        } else {
            kstr = x;
            vstr = '';
        }

        k = decodeURIComponent(kstr);
        v = decodeURIComponent(vstr);

        if (!hasOwnProperty(obj, k)) {
            obj[k] = v;
        } else if (Array.isArray(obj[k])) {
            obj[k].push(v);
        } else {
            obj[k] = [obj[k], v];
        }
    }

    return obj;
};